Oscillation module

Abstract

To provide an oscillation module which is able to improve an input level by passing signals in a main signal band while removing near noise and far noise. An oscillation module is provided with an OCXO, an amplifier, and a noise elimination filter. The noise elimination filter includes: a BPF passing a signal in the main signal band and eliminating far noise with respect to the main signal band; an L-BEF eliminating near noise in a low frequency band with respect to the main signal band; and an H-BEF eliminating near noise in a high frequency band with respect to the main signal band. Each filter is configured with a crystal filter.

1. An oscillation module comprising:
 a crystal oscillator oscillating a signal of a predetermined frequency; 
 an amplifier amplifying the signal output from the crystal oscillator; and 
 a noise elimination filter eliminating noise of the signal which is amplified by the amplifier, 
 wherein the noise elimination filter includes 
 a first crystal filter attenuating a signal in a low-frequency near band with respect to a main signal band of the signal, 
 a second crystal filter attenuating a signal in a high-frequency near band with respect to the main signal band, and 
 a third crystal filter attenuating a signal in a frequency far band lower than the low-frequency near band and in a frequency far band higher than the high-frequency near band while passing the signal in the main signal band, 
 wherein the first and second crystal filters are band attenuation filters, 
 the third crystal filter is a band pass filter, and 
 the first, second, and third crystal filters have the same temperature characteristic. 
 
     
     
       2. The oscillation module according to  claim 1 , wherein the noise elimination filter is configured such that the first crystal filter, the second crystal filter, and the third crystal filter are connected in series in this order with respect to an input signal. 
     
     
       3. The oscillation module according to  claim 1 , wherein a characteristic of the third crystal filter is smooth compared to those of the first and the second crystal filters. 
     
     
       4. The oscillation module according to  claim 2 , wherein a characteristic of the third crystal filter is smooth compared to those of the first and the second crystal filters. 
     
     
       5. The oscillation module according to  claim 1 , wherein the crystal oscillator includes an oven controlled crystal oscillator. 
     
     
       6. The oscillation module according to  claim 2 , wherein the crystal oscillator includes an oven controlled crystal oscillator. 
     
     
       7. The oscillation module according to  claim 1 , wherein the main signal band where the signal is passed through the third crystal filter is 100 MHz±1 kHz;
 a band where the signal is attenuated by the first crystal filter is 100 MHz−10 kHz to 100 MHz−100 kHz; and 
 a band where the signal is attenuated by the second crystal filter is 100 MHz+10 kHz to 100 MHz+100 kHz. 
 
     
     
       8. The oscillation module according to  claim 2 , wherein the main signal band where the signal is passed through the third crystal filter is 100 MHz±1 kHz;
 a band where the signal is attenuated by the first crystal filter is 100 MHz−10 kHz to 100 MHz−100 kHz; and 
 a band where the signal is attenuated by the second crystal filter is 100 MHz+10 kHz to 100 MHz+100 kHz.